1. Field of the Invention
The present invention relates to a semiconductor cleaning device and a semiconductor cleaning method, and particularly to a semiconductor cleaning device and a semiconductor cleaning method for removing foreign matter from a semiconductor device.
2. Description of the Background Art
Semiconductor devices are manufactured through a multiple kinds of processing performed on a semiconductor wafer that is an aggregate of semiconductor devices. In the processing of manufacturing the semiconductor devices, entry of foreign matter occurs in various steps to cause disadvantages in the semiconductor devices. This deteriorates a yield of the semiconductor devices. Therefore, it is desired to remove the foreign matter from the semiconductor devices.
For example, Japanese Patent Laying-Open Nos. 11-087457 and 2011-099156 have proposed devices that can remove foreign matter in a manufacturing process of semiconductor devices. The device disclosed in the above Japanese Patent Laying-Open No. 11-087457 has an electrostatically attracting and transporting arm as well as a plate member for removing foreign matter. From a portion of the electrostatically attracting and transporting arm that is in contact with a rear surface of a wafer, foreign matter is transferred onto the plate member and thereby is removed. Further, the device disclosed in the above Japanese Patent Laying-Open No. 2011-099156 has a transporting arm provided with an electrostatic chuck. A voltage of the same polarity as electric charges of foreign matter adhered to the transporting arm is applied to an electrode of the electrostatic chuck, and a nitrogen gas is blown against the transporting arm to remove the foreign matter.
However, in the device disclosed in the above Japanese Patent Laying-Open No. 11-087457, since the foreign matter is transferred onto the plate member from the portion of the electrostatically attracting and transporting arm that is in contact with the rear surface of the wafer, it is impossible to remove the foreign matter adhered to a side surface of the semiconductor wafer. In the device disclosed in the above Japanese Patent Laying-Open No. 2011-099156, since the electrostatic chuck attracts the rear surface of the semiconductor wafer, it is difficult to remove the foreign matter adhered to a side surface of the semiconductor wafer. Further, the gas is blown for removing the foreign matter so that the foreign matter scattered by the blown gas may adhere again without being removed.
Each of the semiconductor devices which produced by dividing the semiconductor wafer by dicing or the like may suffer from a problem due to presence of the foreign matter in test steps such as evaluation of electric characteristics after the manufacturing steps. For example, when foreign matter adheres to the surface of the semiconductor device provided with a pad for electric connection, it may cause short-circuiting and discharging. These cause disadvantages in the semiconductor device.
In a semiconductor device of a vertical structure that flows a current in a vertical direction, i.e., an out-of-plane direction of the semiconductor device, since not only a front-surface side but also a rear-surface side is used as an electrode, adhesion of foreign matter to the rear surface deteriorates a close-contact property between the semiconductor device and the external electrode. The deterioration in close-contact property between the semiconductor device and the external electrode affects a contact resistance and consequently affects electric properties. In a contact portion where the semiconductor device is in contact with the foreign matter as well as the vicinity thereof, the presence of the foreign matter may cause a defect such as a crack, and thereby may partially break the semiconductor device.
In connection with the foreign matter of individual semiconductor devices, such a fact has been known that, in a process of dividing the semiconductor wafer into semiconductor devices, a large number of minute pieces, scraps and the like of the semiconductor wafer material occur from the side surfaces of the semiconductor devices, and these minute pieces and the like acting as the foreign matter will stay on the side surface of each semiconductor device or the vicinity thereof, and will be brought into a later test step. This kind of foreign matter may move to the front and rear surfaces of the semiconductor device.